The world-renowned science fiction series ‘Star Trek’ mentions a device called the Replicator, which is capable of creating any kind of earthly object—be it a steaming cup of tea or any weapon. Although, at first glance, we might think such a device is impossible to make, nowadays, some people have started to believe that it may not be so impossible after all. Thanks to a technology called ‘Nanotechnology,’ humans are now dreaming of turning science fiction into reality. Over the past few years, research and discoveries in this field have stirred excitement among researchers at various levels. This excitement has now even touched the general public.
What is nanotechnology?—to understand this, we first need to know the meaning of the word ‘nano’. ‘Nano’ is an extremely small unit of measurement. One nanometer is one one-hundred-millionth (one hundred croreth) of a meter, which is even smaller than the wavelength of visible light. For reference, the diameter of a human hair is 50,000 nanometers. From this, we can get a rough idea of just how tiny a nanometer is! Generally speaking, the technology that deals with objects so small they must be measured in nanometers is called nanotechnology, although it cannot be defined so simply. While there is some disagreement among scientists about what size objects fall under this technology, generally, objects ranging from 1 to 100 nanometers are considered within its scope. In 1986, Dr. K. Eric Drexler was the first to use the term ‘nanotechnology’.
Now the question arises—which branch of science does ‘nanotechnology’ belong to? The interesting thing is that it cannot be confined to any single discipline. Biologists, physicists, chemists, engineers—all are involved in this technology. No one has absolute dominance in this realm. However, acquiring in-depth knowledge in so many areas is quite challenging for any one person. Yet, Nobel Prize-winning scientist Dr. Horst Störmer has expressed hope that, among the disciplines related to nanotechnology, a common language will arise, such that well-informed researchers in any branch of science will be able to conduct research in this field without having to master all areas in depth.
The challenge of research in this field is that the conventional laws of physics often do not apply. Here’s a simple example: immerse a straw or glass tube in a glass of water, and you’ll see the water level inside and outside the tube is almost the same—which is normal. But if you immerse an even thinner tube, you’ll notice the water level inside rises above the outside. The thinner the tube, the higher the water rises. Thus, as the diameter of the tube becomes smaller, the normal laws of behavior begin to break down. In the case of objects at the nanoscale, the failure of classical physics laws becomes even more apparent. The properties of nanomaterials cannot be explained by classical mechanics alone, so a new physics is required. Fortunately, several decades before research on nanotechnology began, a new physics had emerged—Quantum Mechanics—which can explain the behavior of objects at the nanoscale.
For example, without climbing over a wall, we can’t get to the other side. But in the nanoscale world, we see that an electron can easily get to the other side of an obstacle without acquiring enough energy to climb it. This seemingly impossible event can only be explained by quantum mechanics. In quantum physics, this phenomenon is called tunneling. Numerous such phenomena occur in the nanoscale world. In other words, to understand nanotechnology, one must abandon old knowledge and start anew.
Recently, scientists have been drawn towards two major breakthroughs in nanotechnology and are conducting relentless research on them: nanowires and carbon nanotubes. Nanowires are extremely fine wires (in some cases, as thin as 1 nanometer in diameter). Scientists hope these can be used to make ultra-small transistors for use in computers and other electronic devices. Over the past few years, the discovery of carbon nanotubes has overshadowed nanowires due to their unique properties. Although we know very little about carbon nanotubes, what we do know is enough to astonish us.
What are carbon nanotubes? Carbon nanotubes are graphene sheets rolled into cylindrical shapes. Graphene is a sheet of carbon atoms, only one atom thick, in which the atoms are arranged in a hexagonal lattice. The way a graphene sheet is rolled determines the nanotube’s properties. In 1991, Dr. Sumio Iijima discovered carbon nanotubes. There are two types—SWNT: Single-walled Nanotubes (made from a single graphene sheet), and MWNT: Multi-walled Nanotubes (made from multiple sheets). The diameter can range from 1 nanometer (for SWNT) up to 50 nanometers (for MWNT), and their length can exceed 1 millimeter. In MWNTs, the gap between layers ranges from 0.34 to 0.36 nanometers.
Carbon nanotubes possess extraordinary properties that have sparked immense interest among scientists. Tests have shown that SWNTs are 50 to 100 times stronger than steel and about six times lighter! Their elasticity is 11.2 terapascal (TPa). Beyond these remarkable mechanical properties, even more intriguing characteristics have been observed. SWNTs conduct heat at twice the thermal conductivity of diamond (which is famous for its high thermal conductivity). Another fascinating property of SWNTs is their electrical conductivity—10⁹ amperes per square centimeter, which is 100 times greater than that of copper! Not only that, but in a vacuum, SWNTs remain stable (i.e., their structure does not change) up to 2,700 degrees Celsius.
So, what can carbon nanotubes be used for? They have countless applications in semiconductor technology, precision instrument manufacturing, medical science, and even in the textile industry. Scientists are highly optimistic about the vast potential of these tubes, especially in electronics. Their use in manufacturing non-volatile memory chips is particularly noteworthy. If the atoms in a carbon nanotube can be arranged properly, they can be made into ideal semiconductor materials. Ultra-small transistors could then be made, making computers and other electronic devices unimaginably small. Currently, CNT-based water and air purification systems are being used, which are capable of destroying bacteria. Their use is also being explored in energy storage cells and batteries. Through these tubes, electrically conductive plastics can be created with immense elasticity. Due to their extremely high electrical conductivity and ultra-fine ends, carbon nanotubes are being used in manufacturing devices related to electromagnetic field emission. Besides these, CNTs are used in various types of sensors, radio frequency devices, bolometers, nanomixers, membranes and valves in medical technology, and more.
Thus, although the history of nanotechnology spans only a few decades, its progress and groundbreaking discoveries have marked the beginning of a new era in science. This technology has become an important branch of science. The boundless curiosity and relentless experimentation of countless scientists are rapidly advancing this technology every day. Nanotechnology is paving the way for humanity to turn imagination into reality. Perhaps the day is not far off when devices like the Replicator will be found in every home. People will no longer just dream of science fiction; they will live it.
Mahfuz
Ami akti university_te pori.
Nanotechnology somporke janar issa onekdin thekai silo. Aj ata pora jetuku jante parlam, tate ami surprised. Ami khusi_te prae kadai falasilam.
Thaknk u mahfuz vai.